2 DATES SET FOR ONOFRE GENERATOR REPORTS

The manufacturer of troubled steam generators at the idled San Onofre nuclear plant says its evaluations of the problem are scheduled for completion at the end of May and August.

Mitsubishi Heavy Industries delivered a sparsely worded interim report to federal regulators about its investigations into the rapid degradation of hundreds of tubes that circulate radioactive water through the San Onofre reactor cores.

Plant operator Southern California Edison is working with Mitsubishi officials, on site since February, to pinpoint the cause of wear from tubes rubbing against support structures and each other.

Federal regulators have placed the onus on Edison to find a solution to the tube wear that can satisfy safety concerns.

Edison indicated Monday that it has completed most of its testing and is developing a plan to eventually bring the two oceanfront reactors back online.

“We’re closing in on being able to state conclusively what we’ve learned,” said Pete Dietrich, senior vice president and chief nuclear officer for Edison, which operates the San Onofre Nuclear Generating Station between Los Angeles and San Diego.

Edison shut down Unit 3 in late January after a tiny radioactive release into the atmosphere was traced to a steam generator leak. Rapid tube wear was discovered at both reactors, though Unit 3 has more substantial problems.

In its report to the Nuclear Regulatory Commission, Mitsubishi said its evaluations were scheduled for completion on May 31 and Aug. 31 for Units 2 and 3 respectively. U.S. representatives for the Japanese conglomerate did not respond to phone calls or an email.

Shaun Burnie, a representative of the nuclear activist group Friends of the Earth, said it would be inappropriate for Edison or nuclear regulators to restart either reactor at San Onofre without the full evaluation by the manufacturer.

Southern California Edison spokeswoman Jennifer Manfre said Edison’s evolving timeline for addressing problems at San Onofre is not dependent on Mitsubishi’s evaluation filing with regulators.

The plant’s generators were replaced starting in 2009 at a total cost of about $670 million. The four replacement generators supplied by Mitsubishi — two for each reactor — are warranted for an initial period of 20 years, according to Edison filings with the U.S. Securities and Exchange Commission.